Sinister Six

The Sinister Six is a villainous team being put together by Gustav Fiers, under the direction of Harry Osborn as a revenge plan against Spider-Man and destroy him. Harry also plans to use this team for his other ends.

Using the Shazam phone app during the end credits of The Amazing Spider-Man 2 will bring the user to 6 images, signifying a possible lineup for the Sinister Six. Besides Green Goblin, Doctor Octopus, Vulture and Rhino, there are two images to do with Kraven the Hunter and Mysterio. However Sony later stated this is not the finished idea for the team.

It is possible that Kraven the Hunter will be a member, as in an interview with Marc Webb mentioned him as one of several characters he's interested in bringing into The Amazing Spider-Man 3, meaning that this is a possible chance that he could be in the Sinister Six movie.

In The Amazing Spider-Man 2 DVD/Blu Ray bonus disc, Marc Webb confirmed that both Mysterio and Kraven will be members of the team.

Usually, in other Spider-Man media, Dr. Octopus was the one who came up with the idea of the Sinister Six, and leaded it. It seems here in this continuity that the Green Goblin will take over the Six.

This isn't actually the first time the Green Goblin became a member of the Sinister Six. In the Ultimate comics, he was part of the team, along with Electro, Kraven, Sandman, and Doc Ock. He was also part of an updated version of the Six, called the Sinister Twelve, in Marvel Knights Spider-Man.